Osteoporosis is a disease of bone in which bone mineral density (BMD) is reduced and bone microarchitecture is disrupted. Osteoporotic bones are susceptible to fracture. It is defined according to the bone mineral density as measured by DEXA: a BMD of 2.5 standard deviations below the peak bone mass (20-year-old person standard) is indicative of osteoporosis. While treatment modalities are becoming available, prevention is still the most important way to reduce fracture. Due to its hormonal component, more women suffer from osteoporosis than men. more...
Signs and symptoms
Osteoporotic fractures are those that occur under slight amount of stresses that would not normally lead to fractures in nonosteoporotic people. Typical fractures occur in the vertebral column, hip and wrist. Collapse of vertebrae ("compression fracture") leads to chronic pain, characteristic bent stature, and decreased pulmonary function (ability to breathe) while the fractures of the long bones acutely impair mobility and may require surgery. Hip fracture, in particular, carries a poor prognosis.
While osteoporosis may occur in men, the problem is overwhelmingly prevalent in postmenopausal women.
Risk factors for osteoporotic fracture can be split between modifiable and non-modifiable:
- Nonmodifiable: history of fracture as an adult, family history of fracture, female sex, advanced age, European ancestry, and dementia
- Potentially modifiable: prolonged intake of the prescription drug prednisone, tobacco smoking, intake of soft drinks (containing phosphoric acid), low body weight <58 kg (127 lb), estrogen deficiency, early menopause (<45 years) or bilateral oophorectomy, prolonged premenstrual amenorrhea (>1 year), low calcium and vitamin D intake, alcoholism, impaired eyesight despite adequate correction, recurrent falls, inadequate physical activity (i.e. too little or also if done in excess), high risk of falls, poor health/frailty.
Dual energy X-ray absorptiometry (DXA, formerly DEXA) is considered the gold standard for diagnosis of osteoporosis. Diagnosis is made when the bone mineral density is equal to or greater than 2.5 standard deviations below that of a young adult reference population. This is translated as a T-score. The World Health Organization has established diagnostic guidelines as T-score -1.0 or greater is "normal", T-score between -1.0 and -2.5 is "low bone mass" (or "osteopenia") and -2.5 or below as osteoporosis. A low trauma or osteoporotic fracture, defined as one that occurs as a result of a fall from a standing height, is also diagnostic of osteoporosis regardless of the T-score.
In order to differentiate between "primary" (post-menopausal, regardless of age, or senile - related to age) and "secondary" osteoporosis, blood tests and X-rays are usually done to rule out cancer with metastasis to the bone, multiple myeloma, Cushing's disease and other causes mentioned above.
Estrogen deficiency following menopause causes a rapid reduction in BMD. This, plus the increased risk of falling associated with aging, leads to fractures of the wrist, spine and hip. Other hormone deficiency states can lead to osteoporosis, such as testosterone deficiency. Glucocorticoid or thyroxine excess states also lead to osteoporosis. Lastly, calcium and/or vitamin D deficiency from malnutrition increases the risk of osteoporosis.
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